All-optical erasable programmable read-only memory (EPROM) based on LiNbO/sub 3/ channel waveguides

The erasable programmable read-only memory (EPROM) consists of three channel waveguides. Two are made by the proton-exchange technique to construct a directional coupler as the read-in and read-out units. The third, placed in between the other two, is made by the Ti-indiffusion technique to function as the memory storage unit as well as the control channel. The operation principle is based on the combination of the directional coupler switch and the photorefractive effect. The EPROM also operates as an all-optical switch if a short-pulsed laser with high-energy density is used to write and erase, and the speed should be on the nanosecond time scale or even faster. Theoretical calculation of some typical designs shows that very small light energy (0.06-0.6 mJ) is needed for the device operation.<>